When the Czech playwright Karel Capek sat down in 1920 to write a play about humanoid machines that turn against their creators, he decided to call his imaginary creations 'robots', from the Czech word for 'slave labour'. Ever since then, our thinking about robots, whether fictional or real, has been dominated by the two key ideas in Capek's play. Firstly, robots are supposed to do the boring and difficult jobs that humans can't do or don't want to do. Secondly, robots are potentially dangerous.

These two ideas remain influential, but not everyone accepts them. The first dissenting voice was that of the great Russian-American science-fiction writer, Isaac Asimov, who was born the same year that Capek wrote his notorious play. In 1940, barely two decades later, while others were still slavishly reworking Capek's narrative about nasty robots taking over the world, Asimov was already asking what practical steps humanity might take to avoid this fate. And instead of assuming that robots would be confined to boring and dangerous jobs, Asimov imaged a future in which robots care for our children, and strike up friendships with us.

From the perspective of the early twenty-first century, it might seem that Capek was right and that Asimov was an idealistic dreamer. After all, most currently-existing robots are confined to doing nasty, boring and dangerous jobs, right? Wrong. According to the 2003 World Robotics Survey produced by the United Nations Economic Commission for Europe, over a third of all the robots in the world are designed not to spray-paint cars or mow the lawn, but simply to entertain humans.

And the number is rising fast. It is quite possible, then, that the killer app for robots will turn out to be not the slave labour envisaged by Capek, but the social companionship imagined by Asimov.